对甲苯磺酸催化合成乙酸正丁酯

用对甲苯磺酸作冰乙酸和正丁醇的酯化催化剂，成功地合成了乙酸正丁酯，考察了影响反应的因素，探讨并找到了较好的反应条件：乙酸l00mmol，n(冰乙酸)：n(正丁醇)：n(催化剂)=1：3：0．006，反应时间1．5h，不另加带水剂，产率达99．14％。     

诱导效应指数与脂肪族胺、醇和醚的气相碱性

用烷基诱导效应指数I和RX分子中质子亲合原子X所带电荷qx及元素电负性XN与 脂肪胺，醇、醚的气相质子亲合PA进行关联，结果表明，脂肪胺，醇、醚的气相碱 性可以用下式定量描述：PA(kJ.mol^-1)-2732.0333-2457.1510∑I-1492.2351qx- 732.6277XN利用上式对64种化合物的气相碱性进行预测，平均相对误差为0．34％ ，预测值和实验值的偏差均在实验误差范围内。     

钯催化下共轭二烯二炔官能团的构成

制备了一系列共轭烯炔化合物以及卤代烯炔化合物,并利用它们在钯催化下交叉偶联构成了与环戊烯共轭骈连的烯二炔即共轭的二烯二炔结构。此结构为抗肿瘤抗生素C-1027发色团和kedarcidin发色团所共有;同时探讨了它们在钯催化下交叉偶连的性质,发现共轭的卤代烯炔与共轭的端炔交叉偶连的趋势为:碘代烯>溴代烯>氯代烯。     

Fura-2探针对希土Y3+跨PC12细胞膜行为研究

使用AR-MIC-CM阳离子测定系统,发展Fura-2荧光测定技术,将其应用于测定细胞内游离希土离子Y³⁺,并以此研究了Y³⁺跨PC12细胞(大鼠嗜铬细胞瘤细胞)膜的行为。结果表明：在模拟细胞内各离子组分,pH=7.05的溶液中,测得表观解离常数为4.5p mol·L^-1。对于PC12细胞,静息条件下Y³⁺不能跨越细胞膜进入胞内。与钙离子通道相关的KCl和去甲肾上腺素均不能刺激希土Y³⁺过膜。用Ouabain(哇巴因)使胞内Na⁺超载后,Y³⁺可过膜进入细胞内,且过膜量与胞外Y³⁺浓度和胞内Na⁺超载程度有一定的浓度依赖关系,提示Y³⁺可以经由Na⁺/Y³⁺交换机制过膜而进入细胞内。     

3,4-二硒方酸芳香性和气相酸性的理论研究

在ＲＨＦ／６－３１１Ｇ水平优化得到３,４－二硒方酸（３,４－二氢硒基－３－环丁烯－１,２－二酮）３ 种平面构象异构体的平衡几何构型。进一步用ＭＰ２（ｆｕｌｌ）／６－３１１Ｇ／／ＲＨＦ／／６－３１１Ｇ方法计算单点能量,发现ＺＺ型异构体是能量最低构象,且ＺＺ和ＺＥ型能量非常接近。用优化的最稳定构象ＺＺ型异构体在ＲＨＦ／６－３１１Ｇ／／ＲＨＦ／６－３１１Ｇ、ＲＨＦ／６－３１１＋ Ｇ／／ＲＨＦ／６－３１１＋ Ｇ、ＭＰ２（ｆｕｌｌ）／６－３１１＋ Ｇ／／ＲＨＦ／６－３１１＋ Ｇ 和Ｂ３ＬＹＰ／６－３１１＋ Ｇ／／Ｂ３ＬＹＰ／６－３１１＋ Ｇ水平计算其气相酸性（ΔＧ°）和同键反应芳香性稳定化能（ＨＡＳＥ）。用基团加和法（ｇｒｏｕｐ ｉｎｃｒｅｍ ｅｎｔ ａｐ－ｐｒｏａｃｈ ） 在 ＲＨＦ／６－３１１ ＋ Ｇ／／ＲＨＦ／６－３１１ ＋ Ｇ 和 Ｂ３ＬＹＰ／６－３１１ ＋ Ｇ／／Ｂ３ＬＹＰ／６－３１１＋ Ｇ水平计算其磁化率增量（Λ）。计算结果指出标题化合物的同键反应芳香性稳定化能和磁化率增量均为负值,表明它具有芳香性,实现了标题化合物芳香性的几何、能量和磁性的判定。     

Structures and stability of N9, N9 − and N9 + clusters

 Ab initio molecular orbital calculations for N₉, N⁻ ₉ and N⁺ ₉ isomers were carried out at the HF/ 6-31G*, B3PW91/6-31G*, B3LYP/6-31G* and MP2/ 6-31G* levels of theory. Stable equilibrium geometric structures were determined by harmonic vibrational frequency analyses at the HF/6-31G*, B3PW91/6-31G* and B3LYP/6-31G* levels of theory. The most stable free-radical N₉ cluster is structure 1 with C _{2 v} symmetry and that of anion N⁻ ₉ is structure 3 with C _s symmetry. Only one stable structure of the N⁺ ₉ cation with C _{2 v} symmetry was predicted. Their potential application as high-energy-density materials has been examined. Received: 15 June 1999 / Accepted: 11 October 1999 / Published online: 14 March 2000     

片状催化剂F-T合成宏观动力学

采用固定床积分反应器,在工业条件下,对压片Ｆｅ－Ｃｕ－Ｋ催化剂进行了Ｆ－Ｔ合成宏观动力学考查。在稳态下,用集总的方法,在保持一定的轴向温度分布及取其平均温度条件下,求得两组宏观动力学方程,两者分别与实验数据吻合较好,同时两者之间也存在较好的一致性。     

聚苯胺对2,5-二巯基-1,3,4-噻二唑氧化还原反应的电化学催化作用的循环伏安研究

研究了聚苯胺(PAn)膜电极在2,5-二巯基-1,3,4-噻二唑(DMcT)溶液中电化学处理或浸泡后的循环伏安(CV)曲线的变化规律.实验结果表明,PAn膜电极在DMcT溶液中进行电化学处理或浸泡过程可使DMcT进入PAn膜内部与PAn形成复合物.PAn对DMcT的电化学催化作用可能和二者之间形成的电子给体-受体复合物有关.该复合物的电化学氧化还原特性不同于PAn和DMcT,其氧化还原反应速率和可逆性均优于DMcT.     

Synthesis, characterization and magnetism of binuclear cobalt (II) complexes bridged by tetracarboxylato groups

Three new binudear cobalt (II) complexes with extended te-tracarboxylato- bridge have been synthesized and characterized, namely [Co2 (PMTA) (bpy)4] (1), [Co2(PMTA)-(phen)4] (2) and [Co2(PMTA) (NO2phen)4] (3), where PMTA represents the tetraanion of pyroniellitic acid, and bpy, phen, NO2-phen denote 2,2'-bipyridine, 1,10-phenan-throline; 5-nirto-1, 10-plienanthroline, respectively. Based on elemental analyses, molar conductivity measurements, IR and electronic spectra studies, it is proposed that these complexes have PMTA-bridged structures and consist of two cobalt (II) ions, each in a distorted octahedral environment. These complexes were further characterized by variable temperature magnetic susceptibility measurements (4-300 K) and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, giving the exchange integral J = - 1.02 cm-1 for 1, J = -1.21 cm-1 for 2 and J = - 1.18 cm-1 for 3, respectively. These results revealed the operation of antiferromagneti     

A stereoselective synthesis of the C(3)-C(13) and C(14)-C(24) fragments of macrolactin A

Synthetic studies towards(he C(3)-C(13)and C(14)-C(24)segments(3,4)of the potent antiviral and antitumor compound macrolactin A(1)are presented.Compound 3 was constructed via a convergent and facile approach,exploiting Wittig olefination to generate the sensitive E,Z-diene moiety.Compound 4 was synthesized from the chiral-pod derived sul-fone 39a via an o-alkylation-desulfonation reaction sequence.Cu(Ⅱ)-catalyzed coupling of a Grignard reagent with an al-lylic bromide and Julia olefination were also investigated for the preparation of compound 4.